东菲律宾海表层沉积物中元素的赋存状态

ELEMENTAL OCCURRENCE PHASES OF SURFACE SEDIMENTS FROM THE EAST PHILIPPINE SEA

为了解东菲律宾海不同类型表层沉积物中元素的赋存状态,采用化学提取方法对有无新型铁锰结壳发育站位表层沉积物样品进行了分级提取及测试,不同类型表层沉积物中成矿和稀土元素的赋存状态总体一致,表明研究区表层沉积物形成于相似的地质和海洋环境中。成矿元素中Fe绝大部分赋存在残渣态中,Mn、Cu、Co和Ni则主要赋存在铁锰氧化物结合态中,稀土元素也主要赋存在这两个相态中,碳酸盐结合态、铁锰氧化物结合态和有机结合态对重稀土元素优先吸附或具络合作用,引起重稀土元素的相对富集和铈的负异常,残渣态优先吸附轻稀土元素,导致轻稀土元素的富集和铈的正异常,火山物质则使表层沉积物残渣态表现出铕的正异常特征。同时,不同表层沉积物样品间也存在一定的差异,这与其局部形成条件——铁锰结壳发育与否有关。

To understand the elemental occurrence phases of different surface sediments from the East Philippine Sea, chemical extraction method has been utilized to extract surface sediments with or without newtype ferromanganese crusts step by step and elements in each phase were measured. The occurrence phases of metallic elements and rare earth elements （REE） of different surface sediments are coherent as a whole, indicating that surface sediments of the studied area were formed in similar geologic and oceanic conditions. Among the metallic elements, Fe mainly concentrates in the residual phase, while Mn, Cu, Co and Ni mainly concentrate in the ferromanganese oxide phase. The REEs also concentrate in these two phases. The carbonate phase, ferromanganese oxide phase and organic phase preferentially adsorb or complexation reacts with the heavy REEs, causing the relative enrichment of the heavy REE and the passive Ce-anomaly. The residual phase preferentially adsorbs the light REE, leading to the relative enrichment of the light REE and the positive Ce-nomaly. The volcanic materials make the residual phase of surface sediments show positive Eu-anomaly character. Meanwhile, there are some differences between different surface sediments, too, which may be correlated with the local environment, that is＇ with or without ferromanganese crust growth.